The present invention relates generally to a containment sump assembly which includes an underground chamber and cover arrangement suitable for enclosing a fill pipe and other tank appurtenances for an underground storage tank and, more particularly, to a containment sump assembly which includes stackable extensions to allow for flexibility in the installation and maintenance of the sump assembly and storage tank.
It is common practice to store flammable or toxic liquids such as gasoline, kerosene, diesel fuel or toxic chemicals in under underground storage tanks. Such tanks usually have an assortment of pipes, such as a fill pipe, vent pipe or product pipe, as well as vapor recovery equipment, pump housing and product level gauge equipment, extending from the underground storage tank upward and usually terminating anywhere from six to eighteen inches below grade level. It is common to provide a containment enclosure for such equipment to protect against ground water and seepage of water from above.
In addition to protection from water seepage, such enclosures are necessary to protect the environment against pollution due to spillage when the underground storage tanks are filled with gasoline, kerosene, diesel fuel or toxic chemicals. Regardless of the type of connection employed during filling operations, spillage occurs either because of poor connections or as a result of over-filling the tanks. Such accidental spillage must be contained to prevent pollution of the ground or water systems within the general vicinity of the storage tanks.
It is further desirable to have a containment assembly which can allow for flexibility in the placement of the sump assembly and underground storage tanks. This is accomplished by providing "stackable" extension members for a standard size containment sump assembly. Such extension members which are designed to "fit" into the containment sump assembly, and into other extension members, provide a means for adjusting the height of the containment sump assembly, during installation of the assembly. Thus, if the underground storage tank is buried at a depth different from that called for by installation specifications, resulting in the height dimensions of the sump assembly being too large or too small, the "stackable" extension members can be used to adjust the height dimensions of the sump assembly and place the entire system at the specified depth in the ground.
A variety of containment sump or manhole assemblies with adjustment or expansion means exist for underground storage tanks or sewage systems. Examples of such devices can be seen in U.S. Pat. Nos. 4,593,714; 4,706,718; 4,302,126; 4,197,031; 4,834,574; 4,469,115; 4,759,656; 4,187,647; 4,690,584; 4,273,467; 3,611,889; 1,639,495; 1,408,982; and 1,165,044. These devices are not entirely satisfactory. Some assemblies are expensive to manufacture and difficult to install; others require threaded screw mechanisms, or clamping mechanisms, resulting in expansion of sections as they are added on or a decrease in the internal diameter of the assembly opening; still others involve the use of certain types of gaskets or sealants which are often exposed to the elements, resulting in degradation of the sealing means and leakage into or out of the assembly. The containment sump assembly with stackable extension members of the present invention provides an improved design which overcomes the problems set forth above.